The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-269428 filed on Sep. 5, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a cooling system for a jet propulsion boat provided with a jet propulsion unit in a pump chamber in a vessel body that is propelled by driving the jet propulsion unit by an engine wherein the exhaust gas is discharged from the engine into the pump chamber.
2. Description of Background Art
The jet propulsion boat is a vessel provided with a jet pump mounted at the rear portion of the vessel body. The vessel is propelled by sucking water from the bottom of the vessel by driving the jet pump by the engine and discharging the sucked water rearwardly. The jet propulsion boat is provided with a cooling system for cooling the engine or an exhaust system with water while being propelled.
A cooling system for a jet propulsion boat is disclosed in Japanese Utility Model Laid-Open No. 86899/1990 that is entitled xe2x80x9cWASHING UNIT FOR VESSEL PROPELLER.xe2x80x9d The cooling system for a jet propulsion boat will be described referring FIG. 1 of this publication that is illustrated hereinafter as FIG. 15 which is a side view showing a jet propulsion boat of the related art.
A jet propulsion boat 100 is provided with an engine-cooling flow path 102 for cooling an engine 101. The engine-cooling flow path 102 takes a part of a jet of water into an intake path 103 as cooling water and guides the cooling water to an engine-cooling duct (as an example, a jacket water) through the intake path 103 for cooling the engine 101 by flowing cooling water through the engine-cooling flow path, and discharges the cooling water to the outside through a drainage duct 105.
The intake path 103 is a flow path being capable of taking a part of a jet of water as cooling water by positioning an intake port 103a toward a jet pump 107. The drainage duct 105 is capable of discharging cooling water to the outside of a vessel body 110 by disposing a discharge port 105a at a front outer wall 110a of the vessel body 110.
The engine-cooling flow path 102 cools the engine 101 with water by providing cooling water during operation of the jet propulsion boat 100. When washing the jet propulsion boat 100, the engine-cooling flow path 102 may be washed with tap water by supplying washing water (for example, tap water) to the discharge port 105a of the drainage duct 105.
Generally, the jet propulsion boat 100 is provided with an exhaust-system-cooling flow path for cooling the exhaust system in addition to the engine-cooling flow path 102 for cooling the engine 101. As a means for cooling the exhaust system, the exhaust-system-cooling flow path is constructed to be provided in series with the engine-cooling flow path 102. In addition, a construction is available wherein the exhaust-system-cooling flow path and the engine-cooling flow path 102 are provided in parallel.
According to the construction in which the exhaust-system-cooling flow path is provided in series with the engine-cooling flow path 102, cooling water used for cooling the engine 101 is also utilized for cooling the exhaust system.
Therefore, since cooling water flows through the engine-cooling flow path 102 and subsequently into the exhaust-system-cooling flow path, the temperature of cooling water in the engine-cooling flow path 102 increases to some extent, which makes preferable control of the temperature of the exhaust system difficult.
On the other hand, according to the structure in which the exhaust-system-cooling flow path and the engine-cooling flow path 102 are provided in parallel, cooling water flowing in the engine-cooling flow path 102 and cooling water flowing in the exhaust-system-cooling flow path are flow separately, and thus it is easy to control the temperature of the exhaust system preferably.
However, when the engine-cooling flow path 102 and the exhaust-system-cooling duct are provided in parallel, washing water has to be diverged and flows simultaneously into both the engine-cooling flow path 102 and the exhaust-system-cooling duct when washing, which results in an increase in the quantity of washing water consumed.
The jet propulsion boat 100 in the above mentioned publication discharges cooling water used for cooling the engine-cooling flow path 102 to the outside through the discharge port 105a of the drainage duct 105. However, since the discharge port 105a of the drainage duct 105 is disposed on the front outer wall 110a of the vessel body 110, the discharge port 105a of the drainage duct 105 can be seen from the outside, which is not preferable in terms of appearance of the jet propulsion boat 100.
Accordingly, it is an object of the present invention to provide a cooling system for a jet propulsion boat in which the quantity of washing water consumed can be reduced and the appearance of the boat improved.
In order to solve the problem, the present invention provides a jet propulsion boat comprising a jet pump chamber provided in the rear portion of a vessel body with a jet propulsion unit provided in the jet pump chamber wherein a jet of water is emitted for propulsion by driving the jet propulsion unit with an engine. A part of the jet of water is taken into an intake path as cooling water. The cooling water taken into the intake path is diverging into the diverging duct and flows into an engine-cooling flow path and an exhaust-system-cooling flow path for cooling the engine and for cooling the exhaust system. A one-way valve is provided that is capable of opening for allowing cooling water to flow from the intake path towards the diverging duct and is capable of closing for preventing washing water from flowing from the diverging duct into the intake path. The one-way valve is provided in the middle of the intake path.
The one-way valve for enabling cooling water to flow from the-intake path into the diverging duct and preventing washing water from flowing from the diverging duct into the intake path is provided in the middle of the intake path.
As a consequent, when operating the jet propulsion boat, cooling water taken into the intake path can flow into the diverging duct through the one-way valve, and cooling water flowing into the diverging duct can be diverged at the diverging duct and flows into the engine-cooling flow path and the exhaust-system-cooling flow path.
On the other hand, when washing the jet propulsion boat, washing water can be prevented from flowing from the diverging duct into the intake path with the one-way valve. Accordingly, it is possible to supply washing water into the engine-cooling flow path for washing the engine-cooling flow path with the supplied washing water and then to supply the used washing water to the exhaust-system-cooling flow path through the one-way valve.
In the present invention a cooling water discharge port of the engine-cooling flow path is disposed in the vicinity of the opening at the rear end of the jet pump chamber.
With the provision of a cooling water discharge port of the engine-cooling flow path in the vicinity of the opening at the rear end of the jet pump chamber, the cooling water discharge port can be hidden by the jet pump chamber. Accordingly, a construction wherein the cooling water discharge port cannot be viewed is realized.
With the provision of the cooling water discharge port in the vicinity of the opening at the rear end of the jet pump chamber, it is possible to insert a hand from the opening at the rear end of the jet pump chamber into the pump chamber and to easily touch the cooling water discharge port with the inserted hand. Therefore, even when tap water is used as washing water, a tap water hose can be attached to the cooling water discharge port relatively easily.
In the present invention a one-way valve is provided with a flow path for communicating a small quantity of washing water from the diverging duct into the intake path when closed.
When the one-way valve is closed, the flow path for flowing a small quantity of washing water (hereinafter referred to as xe2x80x9cfine flow pathxe2x80x9d) can be kept opened, and thus a small quantity of washing water can flow from the diverging duct toward the intake path through the fine flow path. Therefore, the jet pump can easily be washed with a small quantity of washing water passing through the fine flow path.
In addition, by limiting the quantity of washing water to pass through the fine flow path, most parts of washing water used for washing the engine-cooling flow path can flow into the exhaust-system-cooling flow path. Therefore, the exhaust-system-cooling flow path can be washed preferably without taking too much time.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.